Does the body adiposity index (BAI) apply to paediatric populations?

Abstract

Objective: Validation of body adiposity index (BAI) in a paediatrics sample; and to develop, if necessary, a valid BAI for paediatrics (i.e. BAI_p).

Methods: A total of 1615 children (52% boys) aged 5–12 years underwent anthropometry. Their body composition was assessed using a foot-to-foot bioimpedance. The validity of BAI = (Hip circumference/Height^1.5) − 18 was tested by combining correlation and agreement statistics. Then, the sample was split into two sub-samples for the construction of BAI_p. A regression was used to compute the prediction equation for BAI_p-based percentage of body fat (%BF).

Results: The initial BAI over-estimated the %BF of children by 49% (29.6 ± 4.2% versus 19.8 ± 6.8%; p < 0.0001). The original methodology led to a BAI_p = (Hip circumference/Height^0.8) − 38 in children. When compared to BAI, BAI_p showed both better correlation (r = 0.57; p < 0.01 versus r = 0.74; p < 0.0001) and agreement (ICC = 0.34; [95% CI = −0.19–0.65] versus ICC = 0.83; [95% CI = 0.81–0.84]). However, there were some systematic biases between the two values of %BF as exemplified by the large 95% limit of agreement [−9.1%; 8.8%] obtained.

Conclusion: BAI over-estimates the %BF in children. In contrast, BAI_p appears as a new index for children’s body fatness, with acceptable accuracy. In its current form, this index is valid only for large-scale studies.

• Bioelectrical impedance
• body composition
• childhood obesity

Acknowledgements

We are indebted to children (School districts of the North) and their parents for nice participation. We would also like to thank the city councils of Villeneuve d’Ascq and Maubeuge Val de Sambre for their support of the studies.